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Fluconazole increases bactericidal activity of neutrophils through non--cytokine-mediated pathway
E E Zervos1, G W Fink, J G Norman
1Department of Surgery, University of South Florida, Tampa, USA.
Background:
Polymorphonuclear neutrophils (PMNs) preincubated with fluconazole (FCZ) demonstrate enhanced bactericidal activity in vitro.
Objective:
This study was undertaken to determine the role of cytokines in FCZ-induced augmentation of PMN function.
Methods:
PMNs were preincubated with PBS or FCZ and exposed to Escherichia coli. Cell culture supernatants and mRNA were isolated after preincubation and again after exposure to E. coli. Tumor necrosis factor-alpha, interleukin (IL)-1 beta, and IL-8 protein and mRNA levels were determined using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively. Results were compared using the Student's t test.
Results:
Preincubation of PMNs with FCZ resulted in enhanced killing but no difference in cytokine protein or mRNA levels when compared to control. After exposure to E. coli, PMNs significantly up-regulate IL-8 and tumor necrosis factor-alpha independent of the solution with which they were preincubated.
Conclusions:
Up-regulation of the cytokine cascade plays a minor role, at most, in the mechanism through which FCZ augments the bactericidal activity of PMNs.
Insights
Fluconazole (FCZ) enhances polymorphonuclear neutrophil (PMN) killing of bacteria in vitro. However, this effect is not mediated by changes in cytokine levels, suggesting a minor role for the cytokine cascade.
Area of Science:
- Immunology
- Pharmacology
- Microbiology
Background:
- Polymorphonuclear neutrophils (PMNs) exhibit increased bactericidal activity when preincubated with fluconazole (FCZ) in vitro.
- The underlying mechanisms of FCZ-enhanced PMN function require further elucidation.
Purpose of the Study:
- To investigate the role of cytokines in fluconazole-induced augmentation of polymorphonuclear neutrophil function.
- To determine if cytokine production is altered by FCZ preincubation and subsequent bacterial challenge.
Main Methods:
- PMNs were preincubated with either FCZ or a control solution (PBS).
- Cells were subsequently exposed to Escherichia coli.
- Cytokine (TNF-α, IL-1β, IL-8) protein and mRNA levels were quantified using ELISA and PCR.
Main Results:
- FCZ preincubation enhanced PMN bactericidal activity without altering basal cytokine levels.
- Exposure to E. coli induced significant upregulation of IL-8 and TNF-α in PMNs, irrespective of FCZ preincubation.
- No significant differences in cytokine mRNA or protein levels were observed between FCZ-treated and control groups.
Conclusions:
- The cytokine cascade plays a minimal role in the mechanism by which FCZ enhances PMN bactericidal activity.
- FCZ's augmentation of PMN function likely involves pathways independent of significant cytokine modulation.